The Obama administration appears poised to approve a proposed $7 billion Canada-to-Texas Keystone XL oil pipeline despite a series of increasingly passionate public protests in recent weeks, both in Washington and in the environmentally sensitive areas the project would cross.

The State Department, which must approve the proposal for it to go forward because the pipeline originates in Canada, appears to be leaning toward approval after Friday’s combative final public hearing in Washington.

Protesters gathered outside the Ronald Reagan Building and International Trade Center early in the morning, and then filed into the hearing room, where many pleaded with the State Department to reconsider its support for the pipeline. Supporters, which include both business and labor groups, say the project will provide needed energy from a reliable ally, reduce the nation’s reliance of overseas suppliers, and create thousands of new construction and maintenance jobs.

Those economic benefits are overstated, critics say, and that the project bisecting the nation’s midsection will wreak environmental havoc on sensitive land.

State Department officials will now review public comments, and wrap up a 90-day review period in mid-November. Then, it will issue its decision to the White House in December. President Obama has faced pressure from environmental groups, including a series of protests outside the White House, as the decision day has neared.

At Friday’s packed hearing, Robin Mann, director of the environmental group Sierra Club, said she had come from Pennsylvania to make her voice heard. She hopes the State Department will take her concerns and those of other pipeline opponents seriously.

Activists conducted a “sleep-in” Thursday night, allowing dozens of pipeline opponents to move to the front of the line at Friday’s hearing, which was attended by more than 800 people.

“These people were not paid, not bused here,” Ms. Mann said. “These are people who took off work to attend these hearings. They are not convenient times, but this is important enough for them to attend.”

Opponents to the pipeline say it could endanger hundreds of miles of pristine American heartland from Montana to Oklahoma, with particular concerns for Nebraska’s Ogallala Aquifer, the underground source of drinking water and irrigation water for much of the Midwest. Nebraska’s Republican Gov. Dave Heineman and the state’s Republican U.S. Sen. Mike Johanns are working to block the pipeline’s approval.

“This pipeline is not in our nation’s best interest,” Ms. Mann said. “It is dangerous, dirty and unnecessary. The environmental risks are too great for the benefits of this pipeline.”

To keep the pipeline running, electrical-pump stations along the 1,700-mile stretch would have to step up production. That could lead to higher electricity costs for locals and more greenhouse gases polluting the air.

Environmentalists point out that 12 spills occurred during the first year along the constructed portion of the pipeline, Keystone 1.

“Frankly, the industry is not prepared to clean up the pipeline, it’s not prepared to clean up these spills,” said Erich Pica, president of Friends of the Earth. “We already know this thing is going to spill.”

But Canadian pipeline industry officials said at the hearing that the extent of the spills from existing pipeline routes has been greatly exaggerated. Numerous speakers pointed to both the direct and indirect employment impact of the pipeline’s construction.

“The United States has a choice of receiving more oil from its most secure, most stable and most reliable trade partner, Canada, or to continue to import from less-stable locations that do not share the interest and values of Americans,” said TransCanada President and CEO Russ Girling.

“One way to help out the people who are missing out on the wealth is by creating good jobs,” said David Miller, spokesman for Laborers’ International Union of North America, “and that’s exactly what this pipeline would do.”

Sen. Lindsey Graham, South Carolina Republican, last week offered three reasons to approve the pipeline. First, it will create jobs, some 13,000 constructions jobs and 7,000 manufacturing jobs. Second, it will increase the nation’s energy supply, and make the country less dependent on overseas oil. Third, Canada is more sensitive to the environmental impact than are Middle Eastern oil countries.

For a nation struggling to find jobs, the pipeline is too good of an opportunity to pass up, Mr. Graham said. That’s perhaps the most likely reason why the Obama administration would shun environmentalists and approve the pipeline project.